Newbie- Looking for an affordable engraver

[Cheech]

I couldn't agree more Jeff.

Zax, thanks again for sharing your wisdom, know-how, and experiences. I'll be sure to do my homework now that I have a better idea of what to look for in a laser. I'm going to try getting in direct contact with some vendors on both sides of the pond and see what they have to offer.

There is one thing concerning the focal length of the optics that I want to be crystal clear on. When looking for a more powerful laser, are smaller size focal lengths better? or are larger lengths more powerful? you suggested a range of 50-65mm and I'm wondering which end of the scale I should be more impressed with.

thanks,
cheech

[zax15uk]

The ZnSe lenses required for CO2 laser wavelength (10.6um) are more expensive than regular glass lenses. This means it is an area to save money which results in reduced performance.

In general these lenses are Plano-Convex or Meniscus design, the latter provides slightly better performance and is becoming more common. It is also slightly more expensive due to double sided machining.

The longer the focal length, the more depth of field. This usually means you have a larger spot size (lower power density) but maintain it for more depth. This would be suited to cutting thicker materials, and not producing fine engraving work. On the flip side, a short focal length would give a small spot size and more power density, ideal for fine engraving but would quickly expand past the focus point and then lose power and produce a less straight cut. It is more suited to engraving and thin cutting. I suggested a 50-65mm focal length based on your inputs for application. In practice you'll probably find the manufactuer offers a 55mm or similar lens.

I hope this answers your question and isn't too much information.

I've also included a sketch (it was a very quick one) that shows the lens, laser beam and their interaction. The curve of the lens is what sets the focal length so the less curve the further away the focus point but the longer the depth of field (area where the laser is still focused) and larger the spot size.

Zax.

[Cheech]

I think I'm following you Zax. Lets see if I have it right, a 45mm lens would be geared towards engraving work (smaller spot size), while a 65mm lens would be better for cutting (larger spot size). Thanks for the drawing by the way, helps to visualize it.

[zax15uk]

You are close. It's not really the spot size but the depth of field (distance at which the beam stays 'in focus'), however the spot size would be smaller providing a higher power density.

A long focal length in this application would be more like >80mm and a short focal length <50mm with 'normal' being between the two. If you want a general purpose machine get something around 55mm.

Zax.

[Cheech]

Great, I'll shoot for around 55mm then. Thanks again Zax. I might be waiting a couple months before making my purchase, but I will be sure to post when I do.

Have you ever considered making a Faq/guide for newbies Zax?

[nobacoutinho]

Originally Posted by Cheech Great, I'll shoot for around 55mm then. Thanks again Zax. I might be waiting a couple months before making my purchase, but I will be sure to post when I do. Have you ever considered making a Faq/guide for newbies Zax?

I agree with this sugestion. In portuguese will be better for me.

[zax15uk]

I might struggle a bit with Portuguese but good suggestion

Zax.

[nbellowe]

I know this forum is unused for a while, but I'm also a newbie and just wanted some advice. Im planning on using this for almost purely engraving on electronics. I need help picking a laser. Im really good with computers, and use CS5. I have a mac, but have access to a PC if it is necessary.
http://cgi.ebay.com/Brand-New-40w-50...item255d17b7e6
http://cgi.ebay.com/CO2-LASER-ENGRAV...item3a5e931900
I know the second one is likely much much better, but will the first one work for my purpose. Is there a different one you would reccomend. Thank you so much for your help.

[MonoNeuron]

Nbellowe,
Engraving on electronics opens up a new can of worms for you.
Are you trying to engrave on the copper or are you going to engrave on components.
If you want to engrave on the board then you would use a YAG laser because the copper is more susceptable to laser engraving at that wavelength. CO2 wavelengths will just reflect off the copper surface. Copper also dissapates the heat of the laser very quickly as does brass or copper compounds. Some CO2 lasers use copper reflectors in them for the beam propagation along the tube.

If you want to engrave on the components then you will have to work out whether it is ceramic coated, plastic, metal, etc. All are completely different when it comes to what can easily make a mark on them and at what power setting.

It's a pretty broad question you've asked and I think you need to be a little more specific on what you want.
Rich.

[nbellowe]

Originally Posted by MonoNeuron Nbellowe, Engraving on electronics opens up a new can of worms for you. Are you trying to engrave on the copper or are you going to engrave on components. If you want to engrave on the board then you would use a YAG laser because the copper is more susceptable to laser engraving at that wavelength. CO2 wavelengths will just reflect off the copper surface. Copper also dissapates the heat of the laser very quickly as does brass or copper compounds. Some CO2 lasers use copper reflectors in them for the beam propagation along the tube. If you want to engrave on the components then you will have to work out whether it is ceramic coated, plastic, metal, etc. All are completely different when it comes to what can easily make a mark on them and at what power setting. It's a pretty broad question you've asked and I think you need to be a little more specific on what you want. Rich.

I must have worded it wrong. I meant back of laptops/ipods.... etc... Sorry!

[kabli]

Hi cheec
as advice you can see my comparison at
http://www.cnczone.com/forums/showthread.php?t=93362
No. 16 & 22.
for the adobe with eplog. eplog will give you a printer driver and it not that easy to print from it, we never did it, ws used only coralDraw with eplog. Chinese do have program called Lasercut, it is very strait forward to be use, you have to import your file and send it to laser, but i do think ether you go for Chinese or eplog you need a third party program like
http://www.gravograph.com/English/en...g_software.php

mohammad

[kabli]

hi Cheech.
sorry for miss spilling your name before, I will never be good in English spilling.
the other software is very good as I think , I have plan to order it next month.
http://www.photograv.com/
Mohammad